Furnace



June 14, 1927.

J. w. FREMAN warms Filed Ont. 10, 1924 V Patented June 14, 1927.

f r 1,632,730} I JOHN WILLIAM FREMAN, OF SOUTH CARLTON, AUSTRALIA.

FURNACE.

Application filed October 10, 1924. Serial No. 742,910.

tion on line IIII in Fig. 1 through the In the utilization of'coa-l as a fuel in boiler furnaces the problem of attaining such a high degree of combustion that the passage to the fiue'of gases and the promotion of 5 smoke will be reduced or eliminated, has 0ccupied the, attention of many minds'over a long period of time and the methods adopted for the prevention of smoke have extended alongwidely different lines. This problem has been the concern of the applicant for manyyears and a close study of same under practical. conditions and following numerous experiments has revealed that smoke promotion arises from the fact that the extent of area above the the bars in thefurnace tube and within which combustion is effected has not been taken into consideration.

In most types of furnaces in which coal is burnt'the furnace tube has for the purposes of strength and stability been constructed as a cylinder and the fuel carrying surface of the grate has been located below the horis zontal centre line or diameter of the cylinderl As a consequence the space above the grate is considerable and permits the gases,

evolved by the process of combustion of the fuel, to mix and escape unburnt from the greatest zone of heat and to pass out of the 1 furnace'tube as smoke. v

It is well recognized that the escape and commingling of the said gases promotes smoke and it obviously follows that if same can be prevented then smokeless combustion can be attained.

1 is va vertical longitudinal section Lancashire type. v

Figure 2 being a vertical transverse sec- Now according to this invention the obof the front end of a boiler of the ordinary furnace tubes. a a

The full line position of the upper surface 3 of the furnace tube 3 is in accordance with the present invention and it will be noted that the upper surface of the fire bars coincides with the plane passing through the horizontal diameter indicated by the center line c-7 of the semicylinder forming the lower half of the tube so that the space above the firebar to the top 3* of the tube is considerably less than the space below the fire bar to the bottom 3 of the tube.

Referring now to Figure 2 it will be noted that the surface of the furnacetube 3ab0ve the fire bars i'does not coincide with the circumferential line of a sector of a circle but that the vertical portions proceed in a straight line and the upperiends of such portions merge into an arch of comparatively zero curvature.

In Figure 2 the line 5 indicatesthe top edge of the usual furnace bridge.

As the shape of the tube furnaces 3 above the fire bars 4 is not theusual cylindrical shape it is desirable to specially support same against collapsing pressure as by means of the stays 6 from the shell. 7 of the boiler and also by making the furnace tube in short sections.

The staying and jointing of the short sections of thetube will be carried out in any well known manner and in accordance with regulations in force regarding the manufacture and testing of boiler furnaces.

ssh

The height of the upper arch portion of the furnace tube 3 above the fire bars will be determined by the character and quality of the coal being used on the fire bars and as coal produced in various parts'of the world varies in quality over a wide range,

it is not possible to define such height with-' in fixed limits.

It may, however, be stated that from experiments, conducted with average quality black coal used for steam production and obtained in Australia, it has been found that the height inthe ordinary cylindrical tube havinga diameter of three feet should be lowered approximately six inches towards the horizontal centre line of such a tube. I claim In furnaces, a furnace tube of uniform cross section wherein the upper portion above the fire bar has straight vertical sides .lnerging into a flat arch and the lower per- 5 tion of the tube is seinicylindrical and a fire bar in said tube so located that its upper surface coincides with the plane passing through the horizontal diameter of the semicylindcr forming the lower half of the tube so that a restricted area is provided above 10 said bar and :1 correspondingly enlarged area is provided below said bar.

Dated this 7th day of August 1924.

JOHN V. F REEL KN. 

